Strength Parameters of Debris Using a Large Shear Box Apparatus: Application to a Case History

The paper shows the back-analysis results of a shallow landslide occurred on 10 November 2014. A very intense rainfall (that occurred after a prolonged rainy period) caused a number of landslides in the area of Leivi (Liguria, Northern Italy). The considered slope consists of shallow debris overlying the bedrock (Argille a Palombini). The analyses were carried out using the limit equilibrium method. Debris characterization was carried out by means of direct shear tests. For such a purpose, direct shear tests on large specimens were carried out using a large shear box (300 × 300 × 100 mm). The specimens were reconstituted in the laboratory using the soil collected just above the sliding surface. The direct shear tests were performed to determine the effective strength parameters according to different density and water content. Direct shear test results showed that the friction angle values decrease and the cohesion increases, as water content increases. Furthermore, previous geological and geomorphological studies of the area affected by landslides were used to define the study model.